ICS subscription size

Questions
1

Your question

Hi,

When subscribing to an ICS link, what is the max size Stalwart will accept?
I’ve got one that is rather big (13mb) with loads of events, but I’m not sure what stalwart setting will impact this.

Trying to subscribe to it fails at the moment.

Kind regards

2

The limit that applies here is maxICalendarSize on the Calendar singleton, which caps the size of an iCalendar (.ics) file the server will accept. It defaults to 512kb, so a 13MB ICS feed would be rejected outright. You can raise it via the WebUI (Settings › Calendar & Contacts › Calendar) or with the CLI:

stalwart-cli update Calendar --field maxICalendarSize='20mb'

Keep in mind that raising this limit interacts with other calendar limits too, particularly maxRecurrenceExpansions (default 3000) and maxAttendees (default 20), since a large ICS with many recurring events could still be rejected or truncated at those stages even after the size limit is increased.

Reference: Calendar | Stalwart

This is an automated reply from the Stalwart Help Bot. Other community members may follow up if this answer is incomplete or wrong.

3

Even after upping the limit to 20mb this fails. The file itself (when downloading the ics) is 13mb - verified. Upping the recurrence and attendees didn’t make any difference.

Note: not talking about uploading an ics file, i’m subscribing an ics link.

4

It depends on what you mean by subscribe. Stalwart itself doesn’t fetch or host an external ICS feed; a subscribed calendar is normally your client (Apple Calendar, Thunderbird) pulling the remote URL directly, and in that case no Stalwart setting governs the size, and the failure is on the client or the remote host.

If instead you’re importing or PUTting the 13 MB ICS into a Stalwart calendar, raising the iCalendar size limit alone isn’t enough: the DAV request body has its own separate cap, and there’s the HTTP listener body limit above that, so you’d need to raise those too. Can you tell me exactly how you’re subscribing (which client, or which UI action), and what shows up in a trace-level log when it fails? That’ll tell me which path you’re on.

5

I’m subscribing using the bulwark client.

6

Please ask Bulkwark to assist you debugging this issue. I do not know what you mean by subscribing in Bulwark. JMAP for Calendar subscriptions are to Calendar objects, not to ICS links.